Thermosensor question
 

Does anyone know the part no. for the coolant thermosensor that is located above the thermoswitch on the back of the water pump. The parts diagram lists 3 or 4 and I can't tell which is which. It has a green connector plugged into it. Thanks.

Just call Malloy - you don't need a part number.

Dale

I know, but I want to get it tonight before the dealership by my house closes, and I don't trust them to give me the right one without me telling them the actual part number. The people they have working the parts counter at night are pretty clueless.

NF02-18-840. Just got one yesterday myself.

can I buy just the pigtail for the thermoswitch? The wire snapped off of mine right at the connector.

I just ordered a NF02-18-840 since mine was broken.....does anyone know exactly what this sensor does? What symptoms would my car have if it was bad / not hooked up?

I also replaced my thermosensor (the one on the lower back-side of the water pump) and my wire also snapped off. It's a spade connector (female I think) and that's how I fixed it. It sends water temp info. I believe but how the info. is used I haven't a clue. I am interested in the thermosensor located on the num. 2 fuel rail if any can say something about it.

A friend of mine said that that sensor didn't do anything important. I wouldn't think Mazda would put in a sensor that doesn't do anything....but maybe it something stupid that I don't need. I'm trying to figure out if that sensor is why my car won't start easily until it is warmed up.

Accoring to Ray Crowe, that sensor (one with green 2 pin connector) sends the temp signal to the ECU to tell it what the coolant temp is. Unfortunately, I don't know if it is contributing to your problem or not.

If the sensor goes out this can effect the AFR's of the engine. This is one of the inputs the ECU gets in order to pick the fuel map. In other words, its important and the wires shouldnt be clipped.

If the thermosensor is disconnected the ECU sets the coolant temp value to 180. So cold starts could be a problem.

Now my question is, once I put in the new sensor....will the car have to be re-tuned? Someone was saying that it may add too much fuel when the sensor is bad and when the sensor is re-placed that it may lean out my map.

You shouldn't have to, ECU is reading what the sensor reports. If sensor is bad, fuel mixture may be off because of the bad data. Fuel enrichment is in the ECU map, not the sensor.

Sweet....I will have to let you guys know on Wednesday if it works!

I have trouble starting my car for the longest time after my rebuild, I thought it was my fuel enrichment map, or maybe of my 9's plug. Dale Clark had a look @ my car last weekend in attemp to correct my map value and only to find out my coolent temp sender was not working. I have ordered a new one from Ray, and it only costs around $30, and it would have direct affect on cold start. My PFC reads _ _ _ _ on the water temp reading. Does anyone have the PFC reads the same Nil reading when their coolent temp sender went bad? I would assumed a bad sender would give incorrect reading, but not "zero" reading?

On my datalogit.....my water temp reading was 175C which was far from correct....I didn't look at the Commander.

What about using the FC thermoswitch?

Monkman, this thermoSENSOR is use by the ECU, for fuel map calculations. It is not the same as the thermoSWITCH , which is used to turn the cooling fans on & off.


-s-

Update.....I put the new sensor in and it seemed like it made the car start easier....but it would still stall 3 seconds later......Still takes 10 - 15 minutes to start acting right (idle correctly). Up until the car is warm...it hunts badly. I am wondering if now I just have to adjust my idle.


The really bad news is that it seems as if it completely changed my tune......The car stalls often and takes a while to start now. Also, when I was getting on it.....the air to fuel was about 13 to 1 instead of 11 to 1. I am too scared to mess with it right now....I guess I will just put the bad sensor back in for now until we have a tuner come out again. Anyone else have experience with this?

The PFC's stock coolant temp map is a little on the lean side - do some searching on the PFC forum, I posted my settings a few weeks back.

If that sensor was giving faulty readings, it will throw off a lot of stuff - that's a primary sensor for the ECU. That's why it's a good idea to make sure everything's kosher before tuning :).

I would make sure the root of the problem you have now is the sensor and not something else that got messed up in the process of installing the sensor.

Dale

How can this sensor go bad? Can it go bad by a short on the radiator fan relays?

I noticed after that I had a short on one of my relays that my Air fuel ratios have been way off at idle. They are in the high teens.

Also I am wondering where it is located at. Is it the sensor that is located near the front of the water pump housing and does it have that single red and black wire coming out of it?

I just ended up leaving the sensor unplugged.....it didn't fix my problem and changed the whole tune of the car.